OCL in Choco

AIMT : OCL 2 CSP 4 ATLc

OCL AST nodes and UML Object Properties modeled as CSPs using Choco-Solver

These semantics are used in OOCP's compiler's Ecore+XMI and ATL-OCL interpreters.

How get Lib

# download latest version
git submodule add git@github.com:ArtemisLemon/OCLinChoco.git OCLinChoco
# update
git submodule update --remote

//add to settings.gradle
include('OCLinChoco')
//add to build.gradle
dependencies {
    implementation project(':OCLinChoco')
}

Overview

We can split the models into UML CSP and OCL CSP, the former modeling what can be represented with a UML Instance Diagram, and the latter modeling OCL constraints applied to the instance. Attributes and References have their models among the UML CSP, each OCL word - or AST node - has their own set of OCL CSP models.

Typing is represented by the Source interfaces. A PtrSource provides a collection of variables encoding pointers to objects of the problem. A VarSource provides a variable encoding an int in the UML or OCL. Typing is used when choosing which version of a OCL node CSP to apply to a source. Some example signatures:

• + : VarSource * VarSource -> VarSource
• = : VarSource * VarSource -> BoolSource
• size : Source -> VarSource
• asSet : VarsSource -> VarsSource
• isUnique : VarsSource -> BoolSource

Integer Variables as Pointers

This is very much like solving genetif case pronous in English. For example: "My mother's sister's cat's vet's father", would be my.mother.sister.cat.vet.fatherand first we answer who my mom is, then who is/are her sister(s), and so on.

The foundation of these CSP is modeling references with integer variable matricies, of which each variable models a pointer. Those models, along with the NavCSP, allow to identify the problem's variables as part of the problem.

• See RefTable for model of references
• See NavCSP for navigation model, key to modeling ocl queries and structural constraints upon them.

This model was designed to encode ordered multisets of pointers, and has been generalised to represent integer properties. From this encoding, using additional constraints, we can model ordered sets. Using an additional encoding, corresponding to the OccSource type, we model unordered multisets and sets. This additional ecoding is constrainted to match the information in the base one.

NavCSP : Navigation as a constraint satisfaction problem

navCSP : PtrSource * NavTable -> Source

In between the UML and OCL we have the object navigation problem: UML can be used to describe networks of relations between objects, OCL can query that network, and adds vocabulary to describe it more. For example in object.reference.attribute <3 the first part describes a place in the model to find variables, and the end describes a constraint upon the variables found. To find the variables we use the NavCSP.

It is important to type the resulting variables from a NavCSP. To do so we've extended the base navCSP with implementations of the differet types.

UML and OCP support

• UML
  • References with finite cardinality
  • integer attributes
• OCL
  • Navigation
  • Integer Arithmetic (+,-,*,etc..)
  • Integer Relationals (=,<>,<,etc..)
  • Collection Operations (size, asSet, see nodecsp package for full list